Lids of several designs have been devised and used to seal containers. The various designs are dictated in part by the container's structural features and in part by the seal needed. Open-top containers are very prevalent; they range in capacity from a few ozs. to several gallons. Their uses also range from solid or liquid food containment to solid or liquid hazardous material containment. Different degrees of seals are also possible. All of the aforementioned criteria enter into the particular lid design which must be used.
A particulary effective liquid-tight seal is obtained from the class of lids known as center-point compression sealing lids. The lids are used with open-top containers. In these lids, a force is exerted in the center of the lid. The force is transmitted to the lid's periphery to result in substantially equal pressure at the edges. Known center-point compression sealing lids are hinged at one edge. A latching mechanism on the container opposite the hinged edge is used to effect a means to receive force. Means on the container and lid act in concert to provide a very good seal.
A drawback experienced with hinged-type center-point compression lids is the fact the lid is always attached to the containers. As such it can hinder the use of the container. The container is more difficult to fill and empty because of the lid's somewhat bulky presence. However, this known drawback is outweighed by the lid's advantages. As a result various fill and emptying means have been adapted for use on the hinged lid containers.
There has now been devised a lid which has all the advantages of center-point compression sealing lids, yet is completely removable from the container when not needed. The lid member of this invention retains all the advantages of known systems, but not their prime disadvantage.